The Experimental Study On Plate Parameters Affecting The Concrete Expended-Plates Under The Vertical Tension

The Concrete Expended-Plates developed from ordinary concrete filling piles which have the same cross section,it is a new type of pile foundation form that improve the bearing capacity of pile body by adding the Expended-Plates after drilling hole.Its technical principle is: on the basis of the foundation and the soil layer distribution,will be relatively common friction pile in soft soil layer or frictional end bearing pile in pile body position,by special extrusion expansion or screw expansion devices,setting up single or multiple Expended-Plates improve the bearing capacity of the pile,and then make full use of the pile body within the scope of each layer of the bearing capacity of pile endpoint soil,thus improving the bearing capacity of single pile,and achieve the purpose of improving the bearing capacity of single concrete,so as to save cost and shorten the construction period.At present,the theory and test research on the ultimate bearing capacity of pile and the state of soil mass destruction have made great achievements under the compressive state,but the theoretical and experimental study on the ultimate bearing capacity of pile and soil mass destruction under vertical uplift is not perfect enough.In view of the above situation,this paper solves the problem of undisturbed soil under different expanded plate cantilever size and plate slope Angle on the bearing capacity of pile and soil,and experimental study on the effect on the damage state and auxiliary simulation analysis with ANSYS finite element software,and then improve the existing theories on the Concrete Expended-Plates.First of all,from the state of pile soil damage in the test,it can be seen that the Concrete Expended-Plates in the early part of the vertical tensile loading,the soil above the Expended plate is squeezed dense,and gradually with the increasing of load,the dense degree of soil is more and more higher.In this process,the Expended-Plates edge cracks unceasingly develop outward in the soil squeezed dense,this fully shows that the tray thread slip resistance theory is more in line with the actual situation.Secondly,on the basis of the displacement-load curve according to the results of ANSYS finite element software simulation and a small proportion of undisturbed soil model pile test,respectivelystudy changing trend and the destruction of state about the Concrete Expended-Plates displacement-load curve which have different cantilever size and slope angle.The results show that,under vertical tensile load,the longer of the Expended-Plates cantilever length,the higher of the bearing capacity of pile.The scope of influence to the soil above the Expended-Plates is 3 ~ 4 times cantilever length;when the Expended-Plates slope angle is between 30 ° and 45 °,the bigger the Expended-Plates,the lower the bearing capacity of piles.And the most reasonable slope angle is from30 ° to 35 °.Simulation test and model test results are consistent with the small proportion of undisturbed soil experimental research.The model test of this paper is on the basis of prof Yongmei Qian half a pile model test in small scale,perfecting test equipment,test method and test process in order to make the Concrete Expended-Plates load test more convenient,easy to operate.It is unique that model experiment uses the undisturbed soil for the soil sample,which can not only ensure truly reflect the work condition of piles and soil under vertical tensile state,observe and record the whole process of the damage of soil clearly,but also can guarantee the authenticity of the test data and persuasive,contributing to supplement and perfect the existing the Concrete Expended-Plates pulling validated theoretical research,in order to impel the research of the Concrete Expended-Plates and have a wide range of applications.